A large dump truck that travels in a mine has a width (for example, 9 m or so) and a height (for example, 7 m or so) far greater than general trucks and buses. Further, a cab in which the operator sits is arranged on an upper deck located in a front section of the dump truck. Therefore, a small vehicle that exists at a relatively near distance from the operator may enter a blind spot zone and may be hardly visible, and further, it may become difficult to grasp a sense of distance to a preceding vehicle due to a difference in height from the preceding vehicle. Technologies have hence been proposed to mount radar sensors on a mining dump truck for the detection of an obstacle.
As one of the above-described technologies, Patent Document 1 discloses a configuration that plural radar sensors of different detection areas and characteristics are mounted on a dump truck, the same single point is measured with these radar sensors, and a calibration is conducted to improve the accuracy of distance measurement.